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Poster

Session: Session 2 Presenting Authors at Posters (Evens)

P-226 - Role of CLE peptide signaling in AM symbiosis regulation

Thursday, July 17, 2025
13:30 - 15:15  
Location: Confex Hall 3
Local and inter-organ signaling in immunity and mutualistic interactions
Arbuscular mycorrhiza (AM) symbiosis formed between most land plants and Glomeromycotina fungi ranks among the most significant partnerships on earth. Plant control of AM symbiosis involves CLAVATA3/EMBRYO SURROUNDING REGION-RELATED (CLE) peptides and their respective CLAVATA family receptor-like kinases. However, besides the autoregulation of mycorrhizal symbiosis pathway regulated by the MtCLE53-SUNN signaling module, the mechanisms by which other CLE peptides regulate AM symbiosis are little understood. In this project, we investigate the molecular function of a novel AM-induced CLE gene in M. truncatula roots, MycCLE2. Using promoter-β-GLUCURONIDASE (GUS) reporter gene fusions, we found that the MycCLE2 promoter is active in the root vascular tissue and positively correlated with AM colonization levels. CRISPR-Cas9 mutagenesis of MycCLE2 revealed higher AM fungal root colonization levels and significantly higher hyphopodia numbers and longer infection units in knock-out mutants. Together, these results suggest that MycCLE2 is a negative regulator of AM symbiosis. Interestingly, we also found that mycle2 lines have a higher root biomass, which is consistent with reduced root growth observed seedlings treated with synthetic MycCLE2 peptide, suggesting that MycCLE2 also has a negative effect on root development. Future research will determine the mechanisms underpinning MycCLE2 function, including identification of the cognate receptor(s) and downstream signaling pathways.